Chicory is a herbaceous plant. A species of chicory has a root which, when roasted, can produce a substance that has for a long time been considered as a substitute for coffee, and which is also known as "chicory".
Such chicory is presently available in granular form or in powder form. Non-soluble grains are obtained by crushing the chicory root after it has been dried and then roasted. The soluble powder is obtained by atomizing the aqueous extract of chicory.
Soluble coffee has been in existence for a very long time in a granular form in which particles of powder are agglomerated so as to form granules that are larger in size and more homogeneous. That presentation has significant advantages such as improved wettability and is thus more "instant". Presentation in granular form also facilitates flow, transport, storage, and measuring out of the product.
Granularization or agglomerization of soluble coffee powder has been known and used for several tens of years. In particular, in document FR 1 513 730, particles of coffee are wetted in order to make them sticky and they are put into contact in order to form agglomerates, after which water is added in sufficient quantity to lower the softening point of the coffee at its points of contact to a temperature that is sufficient for said points of contact to dissolve; finally, the agglomerates are heated above the softening point so as to melt the particles and dry them. Agglomeration is thus the result firstly of wetting and secondly of localized fusion of coffee particles.
Other techniques have been developed, in particular in document EP 420 509, all of which moisten particles of soluble coffee powders.
The above-mentioned techniques cannot be transposed to soluble chicory powder, since as the presence of moisture leads to an unusable paste being formed. According to the Applicant, this is due to chicory being very hygroscopic due to its high fructose content.
It is thus possible to envisage implementing the above-mentioned techniques of moistening and heating to obtain a chicory-based product in granular form, but only when providing the chicory powder as a small fraction of a mixture with soluble coffee powder, or providing the chicory powder subjected to prior treatment for reducing its fructose content by a significant amount.
Document EP 373 697 proposes avoiding prior moistening of powder particles by performing the heating in a closed environment. In the method described, it is essential to operate in a closed environment so as to retain all of the water content inherent to the powder extract in order to achieve agglomeration. The presence of water, whether by prior moistening or by conserving the natural water content of the powder, is still considered as being essential during heating in order to achieve the looked-for agglomeration.
Document EP 373 697 mentions chicory, but does not give any example relating to this substance. The Applicant has observed that performing agglomeration in a closed environment, without prior moistening, and using chicory in accordance with the teaching of document EP 373 697 leads to an agglomerated product which is not homogeneous, having significant loss of porosity in its surface zone while on the contrary being highly friable in the core of the product. Such non-uniformity makes the agglomerated product completely unsuitable for subsequent crushing and grinding to make granules.
There is another technique for making granules by means of a dry process, implementing high pressure, the powder being agglomerated between two plates, optionally provided with recesses. The slab of powder compressed in this way is subsequently crushed and screened to obtain granules. With soluble chicory powder, that technique using compression leads to an agglomerate that is compact, very dense, and poorly soluble.